Section 19
SEC. 19. Every assignment, license or other instrument relating to any right, title or interest in a copyright and to the work subject to it shall be filed in duplicate with the National Library upon payment of the prescribed fee for registration in books and records kept for the purpose. Upon recording a copy of the instrument shall be returned to the sender with a notation of the fact of record. Notice of the record shall be published in the Official Gazette. Such instruments shall be void as against any subsequent purchaser or mortgagee for a valuable consideration and without notice unless it is recorded in the library prior to the subsequent purchase or mortgage.